1. Field of the Invention
The present invention relates to the field of netting for wrapping spoilable (perishable) items and a method of substantially reducing spoilage of the spoilable items by wrapping the spoilable items with the netting, and more particularly, by wrapping bales using a baling apparatus with the netting.
2. Description of the Related Art
The use of balers for baling agricultural crops into “round” bales (referring to a generally cylindrically shaped bale having a generally round cross-section) has become increasingly common in recent years, replacing the old system of baling square bales that were secured by different types of twine or metal wire. The first round-balers also used various types of twines to secure the bale, however, over the years different types of netting have been used. The use of netting, and in particular, knitted Raschel netting, has become more and more common. Raschel netting is a knitted netting that typically is made from polymeric material and includes a plurality of equally spaced longitudinal ribbons known as “franzes” and a plurality of intervening zigzag ribbons known as “schusses.” However, the netting used, including Raschel knitted netting, is primarily open, with the franzes and schusses only making up a small percentage of the surface area of the bale and does not protect the bales from rain.
Plastic film wrap, including “sticky film” wrap has been used to wrap whole bales or portions of bales, with the goal of protecting a bale from rain.
However, the use of impermeable plastic film wrap does not allow moisture already within a baled crop to escape therefrom, since it is bound by an impermeable plastic layer. Since the inherent moisture level in baled crops may be on the order of one or more dozen percent of weight of the crop (for example, in baled hay), this bound-in humidity easily promotes spoilage of the baled crop.
Moreover, when such plastic film has been used in existing netting systems, typically only a portion of the bale was covered, leaving part of the circumference unwrapped and exposed to rain and/or to moisture from the ground on which the bale is resting. If the entire bale was wrapped with plastic film, then internal moisture could not escape. Likewise, any excess moisture gained by the crop from exposure to weather also promoted spoilage of the baled crop. Since bales are often left in a field, exposed to weather for a year or more, cumulative rain and/or ground moisture penetration may be significant, as may be the resultant crop spoilage.
Another disadvantage of using plastic film as a bale wrap has been that the film does not, itself, grasp onto a bale or underlying film layer, and thus a “sticky” portion had to be incorporated to prevent unraveling of the bale. However, use of such sticky film, even if only a small amount, was difficult to feed into a baler. Reasons for this include that, in the process of loading the film and wrapping a bale, the sticky film stuck to elements of the machine as well, making use of these materials difficult. In order to solve the problem of sticky film sticking to a baling apparatus itself, significant alterations to the baling apparatus had to have been made, often proving not to be cost-effective.
U.S. Pat. No. 4,703,605 to Ackerman describes a bale and baling process using a netting material with water impermeable portion(s) formed from water impermeable foil. In Ackerman, the net and water impermeable portions are not attached to one another, but are fed from either separate rolls, or alternatively are a single piece of material, in which holes are created to form a netting in certain areas, leaving other areas completely sealed off to protect the bale from moisture. Ackerman only covers the bale partially with the water impermeable portion. In Ackerman, only the top, or the top and bottom are covered with such plastic.
German Patent No. DE 3525294 (DE '294) describes a wrapping material for bales having a “watertight film” arranged in a central portion of a netting material. The watertight film has a length equal to at least half the circumference of the bale. No indication is given that it should be anything substantially more than about ½ the circumference of the bale. This watertight film is welded or glued to the net “point by point.” In addition, in DE '294, the netting and the film are fully attached, thus the stretching characteristics of the net are transferred to the watertight film. DE '294 only covers about ½ the circumference of a bale, leaving the remainder of the bale exposed to the elements.
German Patent No. DE 19833554 (DE '554) describes a pre-shaped bale cover for a pre-determined size of bale made up of segments of fiberglass netting attached end-to-end with plastic “foil” segments (note brackets 12 and 14). This end-to-end attachment of segments is significant because the tensile strength of the cover in DE '554 is limited to the weakest portion, which is likely to be the foil segments.
European Patent No. EP 1321028 (EP '028) describes a baler and an enveloping apparatus. Separate rolls of net and sticky (stretch) film, which adheres to underlying net layers, are used. Thus, the layers are not attached to one another prior to assembly.
Published U.S. Patent Application 2004/0121108 (US '108) describes a material and method for wrapping objects with multiple materials in which sequential alternating netting and film segments are used. The netting is not continuous throughout the material, which, like DE '554, prevents the tensile strength of the netting to be of real benefit.
Published PCT Application WO 90/08708 describes a packaging material having breathable paper strip portions and a transparent window strip portion for forming packaging simultaneously with the insertion of a product into the packaging. The strips of the packaging material of WO 90/08708 are arranged side-by-side, attached along adjacent edges, each strip being continuous from the beginning of a roll, to the end of the roll of the material.
Great Britain Patent No. GB 2348633 (GB '633) describes a laminated material in which film is laminated to a netting material. The net offers relatively greater strength than the film portion, but moisture cannot pass through the film portion, and attachment of an end portion of the netting to the bale, to prevent unraveling of the wrapping is difficult. Because of the lamination of the two layers in this reference, negative synergy exists between the netting portion and the film portion. Such negative synergy is a result of, for example, introducing a relatively stretchable component (the film), with a comparatively less-stretchable component (netting).
Typical stretch films for the purposes of wrapping bales experience a reduction in width in connection with an increase in length (stretch). For example a 76 cm wide film used for silage wrapping loses 32% of its width when lengthening 77%. Even if a laminated material has one component with less drastic properties, the laminate as a whole disadvantageously experiences the shape changes of the material with larger shrinkage ratios.